The Collaborative International Dictionary of English v.0.48:

Flaccidity \Flac*cid"i*ty\ (fl[a^]k*s[i^]d"[i^]*t[y^] or
   fl[a^]s*s[i^]d"[i^]*t[y^]), n. [Cf. F. flaccidit['e].]
   The state of being flaccid.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flaccidity
    n 1: a flabby softness [syn: flabbiness, limpness,
         flaccidity]